With respect to an air conditioner comprised of an indoor unit and an outdoor unit, the number of indoor units varies in accordance with the extent of air-conditioned space, and the air-conditioning capacity of an outdoor unit needs to vary accordingly. That is, in the outdoor unit, the sizes of component parts vary in accordance with the degree of a required maximum air-conditioning capacity (for example, Jpn. Pat. Appln. KOKAI Publication No. 2008-133986).